Are Atlantic hurricanes slowing down?

[xmetman]

I read a recent article in the Guardian by Michael Mann saying that recent research had shown that tropical cyclones are slowing down and even stalling, in a similar way to how hurricane Dorian (2019) has recently done over the northern Bahamas and hurricane Harvey (2005) did over Texas. Never wanting to take things I read at face value, I decided to do some research of my own into the subject by means of the HURDAT2 database, and see what a bit of analysis would uncover.

The bar chart is of average annual speed of all hurricanes overlaid with a linear trend that does highlight a reduction in speed of around 10% or 1.4 knots during that time. This reduction more or less ties in with the first of the two studies mentioned in the Guardian article. So the answer is, yes, hurricanes do seem to be slowing down as the first report in Nature suggests.

The second report concerns the stalling of hurricanes on the eastern seaboard of the United States, and is a little more tricky to try and verify. One way that I came up with was to count the 6 hourly speed of all hurricanes and simply keep a tally of when their forward speed was 5 knots or less. Here's the data in the form of another bar chart with overlaid linear trend.

The number of times stalling occurred has decreased slightly since 1945. Admittedly, I have chosen to look at hurricanes over a much larger area (south of 40° north and west of 60° west) than the second study, but this simple analysis shows no real increase in the stalling of hurricanes, even if their average speed has decreased during that time.